The present disclosure generally relates to communications within a building automation system. In particular, the present disclosure relates to methods and devices for communicating change-of-value information within a building automation system.
A building automations system (BAS) typically integrates and controls elements and services within a structure such as the heating, ventilation and air conditioning (HVAC) system, security services, fire systems and the like. The integrated and controlled systems are arranged and organized into one or more floor level networks (FLNs) containing application or process specific controllers, sensors, actuators, or other devices distributed or wired to form a network. The floor level networks provide general control for a particular floor or region of the structure. For example, a floor level network may be an RS-485 compatible network that includes one or more controllers or application specific controllers configured to control the elements or services within floor or region. The controllers may, in turn, be configured to receive an input from a sensor or other device such as, for example, a room temperature sensor (RTS) deployed to monitor the floor or region. The input, reading or signal provided to the controller, in this example, may be a temperature indication representative of the physical temperature. The temperature indication can be utilized by a process control routine such as a proportional-integral control routine executed by the controller to drive or adjust a damper, heating element, cooling element or other actuator towards a predefined set-point.
Information such as the temperature indication, sensor readings and/or actuator positions provided to one or more controllers operating within a given floor level network may, in turn, be communicated to an automation level network (ALN) or building level network (BLN) configured to, for example, execute control applications, routines or loops, coordinate time-based activity schedules, monitor priority based overrides or alarms and provide field level information to technicians. Building level networks and the included floor level networks may, in turn, be integrated into an optional management level network (MLN) that provides a system for distributed access and processing to allow for remote supervision, remote control, statistical analysis and other higher level functionality. Examples and additional information related to BAS configuration and organization may be found in the co-pending U.S. patent application Ser. No. 11/590,157 (2006P18573 US), filed on Oct. 31, 2006, and co-pending U.S. patent application Ser. No. 10/915,034 (2004P13093 US), filed on Aug. 8, 2004, the contents of these applications are hereby incorporated by reference for all purposes.
Wireless devices, such as devices that comply with IEEE 802.15.4/ZigBee protocols, may be implemented within the control scheme of a building automation system without incurring additional wiring or installation costs. ZigBee-compliant devices such as full function devices (FFD) and reduced function devices (RFD) may be interconnected to provide a device net or mesh within the building automation system. For example, full function devices are designed with the processing power necessary to establish peer-to-peer connections with other full function devices and/or execute control routines specific to a floor or region of a floor level network. Each of the full function devices may, in turn, communicate with one or more of the reduced function devices in a hub and spoke arrangement. Reduced function devices such as the temperature sensor described above are designed with limited processing power necessary to perform a specific task(s) and communicate information directly to the connected full function device.
Wireless devices for use within the building automation system must operate for an extended period on a limited battery charge. Systems, devices and methods to maximize power conservation may be desirable to extend and/or maximize the operating life of wireless devices and the network in which they operate.